no-mixed-operators
Disallow mixed binary operators
用小括号将复杂的表达式括起来，可以澄清开发者的意图，从而使代码更易读。 当在一个表达式中连续使用不同的运算符而没有括号时，这条规则会发出警告。
var foo = a && b || c || d; /*BAD: Unexpected mix of '&&' and '||'.*/
var foo = (a && b) || c || d; /*GOOD*/
var foo = a && (b || c || d); /*GOOD*/
注意： 预计该规则会对一对混合运算符发出一个错误。因此，对于每两个连续使用的混合运算符，将显示一个不同的错误，指出哪里使用了违反规则的特定运算符。
var foo = a && b || c || d;
will generate
1:13 Unexpected mix of '&&' and '||'. (no-mixed-operators)
1:18 Unexpected mix of '&&' and '||'. (no-mixed-operators)
规则细节
该规则检查 BinaryExpression、LogicalExpression 和 ConditionalExpression。
此规则可能与 no-extra-parens 规则冲突。
如果你同时使用这条规则和 no-extra-parens 规则，你需要使用 no-extra-parens 规则的 nestedBinaryExpressions 选项。
使用此规则的错误示例：
/*eslint no-mixed-operators: "error"*/
var foo = a && b < 0 || c > 0 || d + 1 === 0;
var foo = a + b * c;
使用此规则的正确示例：
/*eslint no-mixed-operators: "error"*/
var foo = a || b || c;
var foo = a && b && c;
var foo = (a && b < 0) || c > 0 || d + 1 === 0;
var foo = a && (b < 0 || c > 0 || d + 1 === 0);
var foo = a + (b * c);
var foo = (a + b) * c;
选项
{
"no-mixed-operators": [
"error",
{
"groups": [
["+", "-", "*", "/", "%", "**"],
["&", "|", "^", "~", "<<", ">>", ">>>"],
["==", "!=", "===", "!==", ">", ">=", "<", "<="],
["&&", "||"],
["in", "instanceof"]
],
"allowSamePrecedence": true
}
]
}
This rule has 2 options.
-
groups（string[][]） - 指定要检查的运算符组。groups选项是一个组的列表，一个组是一个二进制运算符的列表。默认的运算符组被定义为算术、比特、比较、逻辑和关系运算符。注意：三元运算符 (?:) 可以是任何组的一部分，默认情况下，允许与其他运算符混合。 -
allowSamePrecedence（boolean） - 指定是否允许混合运算符具有相同的优先级。默认为true。
groups
下列运算符可用于 groups 选项：
- 算术运算符：
"+","-","*","/","%","**" - 位运算符：
"&","|","^","~","<<",">>",">>>" - 比较运算符：
"==","!=","===","!==",">",">=","<","<=" - 逻辑运算符：
"&&","||" - 合并运算符：
"??" - 关系运算符：
"in","instanceof" - 三元运算符：
?:
现在，考虑以下组的配置：{"groups": [["&", "|", "^", "~", "<<", ">>", ">>>"], ["&&", "||"]]}。
在这个配置中，有 2 个组被指定：位运算符和逻辑运算符。
这条规则只检查运算符是否属于同一组。
在这种情况下，本规则检查位运算符和逻辑运算符是否混合，但忽略所有其他运算符。
使用此规则并使用 {"groups": [["&", "|", "^", "~", "<<", ">>", ">>>"], ["&&", "||"]]} 选项的错误示例：
/*eslint no-mixed-operators: ["error", {"groups": [["&", "|", "^", "~", "<<", ">>", ">>>"], ["&&", "||"]]}]*/
var foo = a && b < 0 || c > 0 || d + 1 === 0;
var foo = a & b | c;
/*eslint no-mixed-operators: ["error", {"groups": [["&&", "||", "?:"]]}]*/
var foo = a || b ? c : d;
var bar = a ? b || c : d;
var baz = a ? b : c || d;
Examples of correct code for this rule with {"groups": [["&", "|", "^", "~", "<<", ">>", ">>>"], ["&&", "||"]]} option:
/*eslint no-mixed-operators: ["error", {"groups": [["&", "|", "^", "~", "<<", ">>", ">>>"], ["&&", "||"]]}]*/
var foo = a || b > 0 || c + 1 === 0;
var foo = a && b > 0 && c + 1 === 0;
var foo = (a && b < 0) || c > 0 || d + 1 === 0;
var foo = a && (b < 0 || c > 0 || d + 1 === 0);
var foo = (a & b) | c;
var foo = a & (b | c);
var foo = a + b * c;
var foo = a + (b * c);
var foo = (a + b) * c;
/*eslint no-mixed-operators: ["error", {"groups": [["&&", "||", "?:"]]}]*/
var foo = (a || b) ? c : d;
var foo = a || (b ? c : d);
var bar = a ? (b || c) : d;
var baz = a ? b : (c || d);
var baz = (a ? b : c) || d;
allowSamePrecedence
使用此规则与 {"allowSamePrecedence": true} 选项的正确示例：
/*eslint no-mixed-operators: ["error", {"allowSamePrecedence": true}]*/
// + and - have the same precedence.
var foo = a + b - c;
Examples of incorrect code for this rule with {"allowSamePrecedence": false} option:
/*eslint no-mixed-operators: ["error", {"allowSamePrecedence": false}]*/
// + and - have the same precedence.
var foo = a + b - c;
Examples of correct code for this rule with {"allowSamePrecedence": false} option:
/*eslint no-mixed-operators: ["error", {"allowSamePrecedence": false}]*/
// + and - have the same precedence.
var foo = (a + b) - c;
何时不用
如果你不关心混合运算符，你可以安全地禁用此规则。
Related Rules
Version
This rule was introduced in ESLint v2.12.0.